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Our future, our universe, and other weighty topics

Saturday, September 12, 2015

The Design Avoidance Contraption Known as the Cosmic Inflation Theory

The
cosmic inflation theory is often confused with the Big Bang theory,
but it is really just a variation of the Big Bang theory. The Big
Bang theory makes the very general assertion that the universe
started to expand from an incredibly hot and dense beginning 13
billion years ago. The cosmic inflation theory makes a very specific
claim that during a tiny fraction of the universe's first second, the
universe underwent a burst of “exponential expansion” in which
the expansion rate was vastly greater than at any time in the
universe's history. You can believe in the Big Bang theory without
accepting the theory of cosmic inflation.

One
might ask the question: if we already had the Big Bang theory, what
need was there for this cosmic inflation theory? The standard answer
given is that the cosmic inflation theory “fixes problems” in the
Big Bang theory. What were these problems? The first problem is known
as the flatness problem.

There
is a density of matter in the universe known as the critical density,
which is the amount of density that would be needed to stop the
universe's expansion, and cause the universe to begin collapsing
because of the gravitational contraction of matter. Scientists know
that the actual density of the universe is close to this critical
density. When cosmologists consider earlier points in the universe's
history, they find that the match between the critical density and
the actual density must have been even closer, with the closeness of the match being
proportional to how far you go back in time. When cosmologists go back to
the beginning of time, the moment of the Big Bang, they find that the
critical density and the actual density must have matched to about
one part in 100 trillion trillion trillion trillion
trillion, or 1 part in 1062. I use here the figure listed
in the wikipedia.org article on the flatness problem. Why was this
match so exact? This is the flatness problem.

The
second problem is known as the horizon problem. This is the problem
that different parts of the universe (in opposite regions of the sky)
had the same temperature, even though they seem to be “causally
disconnected” so that there is no way to explain their equal
temperatures by assuming anything like a thermal equilibrium used to
explain a uniformity of temperature in a volume of gas.

Although
these issues have been called problems with the Big Bang, they are
not problems at all to someone who believes that the sudden origin of
the universe was a supernatural event. To such a person, the
flatness problem and the horizon problem can simply be indications
that the Big Bang was a carefully designed event, rather than a
random natural event.

There's a phrase used in the computer software
industry when a customer complains about something that was
deliberately put in a computer program. The phrase is: that's not
a bug, it's a feature. A theist could say exactly the same thing
about the flatness problem and the horizon problem – they're not
bugs in the Big Bang, but features of the universe's birth, features
that were put in deliberately so that we could eventually be here in
a nice, orderly, life-bearing universe. It is known that if the
universe's actual density did not exactly match the critical density
at the beginning, we would not have a universe suitable for life –
either the universe would have expanded too rapidly for galaxies to
form, or the universe would have collapsed in on itself because of
gravitational contraction.

Now
thinking such as that may be repellent to many scientists, so it is no
surprise that some scientist would have come up with some theory
designed to explain away these things that may at first seem to be
evidence of a very carefully designed Big Bang. The cosmic inflation
theory is such a theory. If this theory were simple, we might
categorize it as a design avoidance device, since the main
purpose of the cosmic inflation theory is to avoid or evade what
seems to be evidence of design in the universe's birth. But since
the cosmic inflation theory is very complicated,
it is more descriptive for us to categorize it as a design
avoidance contraption. A contraption is some very complicated
thing which seems ugly because of a lack of simplicity.

If
you don't think it is fair for me to call the cosmic inflation theory
a contraption, I will ask you to take a close look at the image
below. This is from a recent scientific paper entitled “Fine Tuning
May Not Be Enough,” by S.P. Miao and R.P. Woodard. The paper
discusses six cases of fine-tuning that are needed to make the cosmic
inflation theory work:

It
is clear from the above passage that the cosmic inflation theory is a
very complicated thing that has many requirements that must be just
right for it work. Note the exponents in the equations above.
Whenever a scientist talks about requirements and starts listing
things carried to the second power or to the third power, it is a
strong sign of very sensitive requirements that must be just right.

Anything
with such a large set of requirements deserves to be called a
contraption. This particular paper notes that “some of these
conditions work against one another,” meaning that if you fine-tune
one of the requirements needed for cosmic inflation to work, you will
tend to mess up some other requirement needed for it to work. In
fact, the paper suggests that there may be no way to get all of these
requirements working simultaneously (and if that's true, the cosmic
inflation theory simply is not feasible). As the paper puts it:

However
distasteful all this fine tuning might seem, it has always been believed
that the thing could at least be done. The purpose of this paper is to
point out that this may not be true.

Now
if there is a lot of fine-tuning required for the cosmic inflation
theory to work, it would seem that the key question to ask is this:
do we actually get a reduction in fine-tuning requirements by
adopting the cosmic inflation theory? We could use this technique to
try to answer that question.

Start
out by calculating the degree of fine-tuning that is required if we
don't believe in the cosmic inflation theory (which would be
something like that fine-tuning to 1 part in a hundred trillion trillion
trillion trillion trillion commonly mentioned in scientific discussions of
the flatness problem).

Then
estimate the total amount of fine-tuning required for the cosmic
inflation theory to work (what the chance would be of all the
conditions for successful cosmic inflation being met in some random
accidental universe).

If
it is found that the theory of cosmic inflation theory requires more
fine-tuning than the fine-tuning tuning it was designed to explain
away or remove (or about the same amount of fine-tuning), discard
the theory on the grounds that it does not produce much of a
reduction in fine-tuning requirements.

What
is astonishing is that I see no evidence that our cosmologists are
actually making such a comparison. Perhaps they don't want to make
such a comparison because it would mess up their pleasant-sounding
triumphant narrative: scientists find a problem with one of their
most fundamental theories, but then a brilliant scientist fixes the
problem. Perhaps it is also that they want to avoid a narrative
such as this: scientists find that the Big Bang was apparently
fine-tuned to an astonishing degree; scientists try to explain that
away with a cosmic inflation theory; scientists eventually find that
theory requires more fine-tuning than the fine-tuning it removes.

We
can compare this situation with that of a Manhattan resident who is
concerned about the money he is spending on subway fares and cab
fares. So he buys a car, believing that this is a money saver. He
figures he is saving $200 a month by not paying for subway fares and
cab fares. But there are many costs associated with the car. He has
the monthly auto payments, and perhaps also a monthly interest cost.
He also has to pay for car insurance. Then he has to pay a hefty
monthly fee for a garage, because there's almost no vacant parking
spots on the streets in Manhattan. Then there's also the fact that
when he wants to drive from one spot to another in Manhattan, he will
often have to pay $15 for parking, because of the lack of available
parking spots on the street. When this person adds up all the costs
of this “money saver” car, he may find that owning such a car is
twice as expensive as just taking the subway and cabs.

Similarly,
the total combined “fine-tuning” cost of all the fine-tuning
required by the cosmic inflation theory may be more than the
fine-tuning supposedly removed when such a theory is believed in. It
could easily be that we are twice as unlikely to have randomly got a
universe performing like the cosmic inflation theory as we would be
to have got a universe that coincidentally started out with the
critical density matching the actual density. Have cosmologists
shown that this is not true? No, because they don't want to do that
math – just as the Manhattan car buyer I just referred to wouldn't
want to do the math showing his poor economic decision.

Copyright Notice

All posts on this blog are authored by Mark Mahin, and are protected by copyright. Copyright 2013-2014 by Mark Mahin. All rights reserved. Any resemblance between any fictional character and any real person is purely coincidental.